<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    * {
      margin: 0;
      padding: 0;
    }

    body {
      width: 100%;
      height: 100%;
      background-color: #000;
    }

    .box {
      width: 1000px;
      height: 1000px;
      margin: 300px auto;
      text-align: center;
    }

    .left,
    .right {
      display: inline-block;
      width: 231px;
      height: 361px;
      background-color: pink;
      border-radius: 125px 125px 0 0;
      animation: tiaodong 1s ease-in-out infinite alternate-reverse;
    }

    @keyframes tiaodong {
      0% {
        width: 231px;
        height: 361px;
        box-shadow: 0 0 0 pink;
      }

      50% {
        width: 211px;
        height: 313px;
        
      }
      100%{
        box-shadow: 0 0 40px pink;
      }
    }

    .left {
      transform: rotateZ(-45deg) translateX(102px);
    }

    .right {
      transform: rotateZ(45deg) translateX(-102px);
    }
  </style>
</head>

<body>
  <div class="box">
    <div class="left"></div>
    <div class="right"></div>
  </div>
</body>

</html>